Nowadays, nanoparticles are studied for many technological applications in various fields, such as medicine, electronics, environmental care, pharmaceuticals, cosmetics, textiles and agriculture. The main interest of nanoparticles is their high surface reactivity; small amount of material has a large reactive surface area and, therefore, provides good results. In remediation zero-valent iron and amorphous magnesium-based alloys, with zinc addition to reduce the oxidation, have been studied. The objective of this work is to evaluate the application of Mg_70 Zn_30 metallic glass powders in to the degradation process of azo dyes (N=N) and compare these results with Fe metallic powders. During this study, the most suitable working method with the equipment available in the laboratories of university has been found. An initial assessment of the ability of the metal compounds as inducers of decolourization was performed. Eventually, the results obtained indicate that the capacity of zero-valent iron is better than that of the semi-amorphous alloy〖 Mg〗_70 Zn_30 in the case of decolourization of Reactive Black 5 dye. However, the results are not good enough for their application in the treatment of textile wastewater effluents which have a pH around neutrality and temperatures around of 25⁰C. However, this study has permitted to optimize the experimental method and it opens the possibility to test the decolourization of other metal compounds.